1. Field of the Invention
The present invention relates to a tube expansion device which can manufacture a heat exchanger through integrating a multiply-polymerized integrating heat radiating fin and a plurality of tubes inserted to the heat radiating fins through pressing a tube expansion mandrel which expands the tube into a tube.
2. Description of Related Art
There exists this kind of tube expansion device published in a Japanese examined utility model application publication 1-23650 as an example as a prior art.
A tube expansion device published in the above publication forms a device main body 14a through a pair of posts 19a being founded with a predetermined distance on a base 19 as illustrated in FIG. 6 and through a top end of each post 19a being connected through a beam member 20.
A reciprocating effector 7 having said tube expansion mandrel 5 causes a guide bar (guide post) 21 founded oppositely to said posts 19a to be inserted and is provided in freely rising and falling (freely reciprocating) fashion through two cylinders 6 at a tube expansion device 14 forming a device main body 14a in accordance with the aforementioned constitution so that an end plate 15a, each of a plurality of heat radiating fins 15b and a tube 16 are integrated by pressing a tube expansion mandrel 5 into a tube opening of a tube 16 of a heat exchanger 15 set at a base 19.
An encoder 13 having a pinion gear 12 meshed with a rack 11 installed in a vertical state in order to measure a lowered distance of said reciprocating effector 7 moving toward a heat exchanger 15 and counting an turning angle of said pinion gear 12 is also provided at the reciprocating effector 7.
In addition, a force pressing plate 9 having a tube outer fitting body 9a to set a protrusion length of a tube 16 protruded from an end plate 15a by pushing down an end plate 15a in contact with said end plate 15a of a heat exchanger 15 is hung at said reciprocating effector 7.
A limit switch 10 detecting start of the lowering of a force pressing plate 9 which lowers to move toward a heat exchanger together 15 with a reciprocating effector 7 is provided at said force pressing plate 9.
Further, one balance cylinder 8 which operates to stop the lowering of a force pressing plate 9 when the lowering distance of a force pressing plate 7 measured by said encoder 13 reaches to a lowering distance set in advance and which measurement is conducted with a detecting signal of said limit switch 10 as a starting signal is provided at the both ends of said force pressing plate 9.
Thus, in a tube expansion device 14 constituted as stated above, a protrusion length of a tube 16 protruded from an end plate 15a of said heat exchanger 15 can be set at any time to a predetermined length by operation of said balance cylinder 8 to stop the lowering of a force pressing plate 9 when a measured value measured through said encoder 13 with detection signal of said limit switch 10 as a starting signal reaches to a predetermined value.
Manufacturing cost of a tube expansion device with the aforementioned constitution would, however, increase, since various equipment, etc. such as a limit switch 10, a rack 11 and an encoder 13 having a pinion gear to be engaged with said rack 11 shall be individually attached to a device,
As a result, a tube expansion device having the constitution illustrated in FIG. 5 has been developed and gone on the market instead of said tube expansion device so as to prevent manufacturing cost increase as mentioned above.
Such a tube expansion device comprises a cylinder 4 equipped with a pulse encoder 18, and has a constitution that a reference platform 1 stopping lowering of a force pressing plate 9 is attached to an expanding and contracting rod 4a of said cylinder 4 through a fixing member 1a such as a male screw.
Accordingly, a tube expansion device having a constitution in the latter of the above does not need a process to operate a balance cylinder 8 after having measured the actual lowered distance of a lowering reciprocating effector 7 which are required for a tube expansion device 14 with a constitution in said above former, and can easily set a protrusion length of an expanding and contracting rod 4a through a pulse encoder 18 in advance.
Therefore, manufacturing cost can be suppressed by reducing a number of various equipment, such as a limit switch 10, a rack 11 and an encoder 13 having a pinion gear to be engaged with said rack 11.    Patent Literature 1: Examined Utility Model Application Publication No. 123650